Nearly all naturally occurring water sources contain fluoride—a mineral that has been proven to prevent, and even reverse, tooth decay.
Tooth decay is caused by certain bacteria in the mouth. When a person eats sugar and other refined carbohydrates, these bacteria produce acid that removes minerals from the surface of the tooth. Fluoride helps to remineralize tooth surfaces and prevents cavities from continuing to form.
In the 1930s, dental scientists documented that the occurrence and severity of tooth decay was lower among people whose water supplies contained higher levels of natural fluoride. Extensive studies followed and discovered that fluoride, when present in the mouth, can become concentrated in plaque and saliva, helping to prevent the breakdown of enamel minerals. In 1945, the city of Grand Rapids, Michigan, added fluoride to its municipal water system. Community water fluoridation—adjusting the amount of fluoride in an area's water supply to a level that helps to prevent tooth decay and promote oral health—had begun. Since then, numerous scientific studies and comprehensive reviews have continually recognized fluoridation as an effective way to prevent tooth decay.
Water fluoridation prevents tooth decay mainly by providing teeth with frequent contact with low levels of fluoride throughout each day and throughout life. Even today, with other available sources of fluoride, studies show that water fluoridation reduces tooth decay by about 25 percent over a person's lifetime.
Community water fluoridation is not only safe and effective, but it is also cost-saving and the least expensive way to deliver the benefits of fluoride to all residents of a community. For larger communities of more than 20,000 people, it costs about 50 cents per person to fluoridate the water. It is also cost-effective because every $1 invested in this preventive measure yields approximately $38 savings in dental treatment costs.
This method of fluoride delivery benefits all people―regardless of age, income, education, or socioeconomic status. A person's income and ability to get routine dental care are not barriers since all residents of a community can enjoy fluoride's protective benefits just by drinking tap water and consuming foods and beverages prepared with it.
Fluoride from other sources prevents tooth decay as well, whether from toothpaste, mouth rinses, professionally applied fluoride treatments, or prescription fluoride supplements. These methods of delivering fluoride, however, are more costly than water fluoridation and require a conscious decision to use them.
Currently, more than 204 million people in the United States are served by public water supplies containing enough fluoride to protect teeth. Even so, approximately 100 million Americans do not have access to fluoridated water. Healthy People is the plan that sets health goals for the nation. This plan calls for about 80 percent of the population to be served by optimally fluoridated community water systems by 2020. The current population with access to fluoridated water is approximately 74 percent.
The widespread availability of fluoride through water fluoridation, toothpaste, and other sources, however, has resulted in the steady decline of dental caries throughout the United States.